ENSO-neutral conditions persisted in the tropical Pacific during May 2018. Sea surface temperatures (SSTs) in the central and eastern equatorial Pacific Ocean continued to warm during May and are now near or slightly above average. The NINO3.4 is currently close to zero (+0.01°C for May 2018).
In the subsurface ocean, (within the first 150 metres of the ocean) positive temperature anomalies extend from the western Pacific (near 160°E) to the South American coast. Significant positive anomalies (> +3.0°C) have now persisted in the central Pacific (170-150°W), centred at about 125-150m depth, for the third consecutive month while another area warmer than +3.0oC developed around 50m depth in the eastern Pacific between 130-95°W.
The Southern Oscillation Index (SOI) has gradually decreased over the last 3 months and is currently neutral with a value of +0.3 for May 2018. April and May 2018 rainfall and convection anomalies in the tropical Pacific were significantly different than the preceding two months. Convective activity is now centred over the western Indian Ocean and Africa, a stark change from the La Niña-driven pattern (of convective forcing in the West Pacific) during early 2018.
The analysis of several atmospheric and oceanic indicators showed that the climate system remained in an ENSO-neutral state during May 2018. The presence of warmer than average subsurface ocean waters in the Pacific, warming NINO indices, and convective anomalies that lean in the direction of El Niño may indicate the direction of the system for later in 2018. In the meantime, ENSO-neutral is expected to continue over the next several months (67% chance over June – August 2018). The forecast models then favour El Niño conditions during the late winter and spring (August – October 2018).
Download the report: Island Climate Update June 2018 [3.4MB PDF]